Before that, Amaraweera, Basil Rajapaksa and Dinesh Gunawardena had a preliminary round of talks.
According to the proposals, president Maithripala Sirisena and Mahinda Rajapaksa will decide the leader and the chairman of the new alliance.
The SLPP has asked for the secretary and treasurer positions.
Also, it wants the executive committee members appointed on the basis of the percentage of votes gained by each affiliate party at the last local government polls.
The two parties expect to form the alliance by next month.